firewall blocking of loopback connection

Hi,

My question, in short, is:

Are software firewalls in their default configurations likely to block a connection from a program *to itself*?

Background:

I am working on a thick-client application that serves a lot of content as locally generated and modified web pages.

I've embedded a webserver in that client so that it serves up pages like http://localhost:/path/to/content/.After loading the pages AJAX is used to update the pages.

This approach provides a lot of functionality I want, but I want to avoid any problems with end-users' firewalls blocking the localhost connection, or annoying them with warning messages.

I'm sure that these connections *could* be blocked -- my question is whether such connections are likely to be blocked. For example, would they be blocked with the default configurations of popular firewalls. First of all I'm interested in {Windows XP, Windows Vista} x {Windows Firewall, Norton Firewall, ...}. But I'm also interested in Mac or Linux data.

Thanks a lot, David